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The mechanism of injury usually involves either blunt or penetrating trauma. While relatively protected by the mandible above and the sternum below, the larynx may be crushed between a blunt object and the cervical spine. Strangulation type injuries result mainly in cartilage fracture while high speed injuries such as motor vehicle or sports related accidents often have both cartilage injury as well as soft tissue injuries related to endolaryngeal shearing forces. Arytenoid cartilage dislocation and recurrent laryngeal nerve injury may also be present. Cervical spine injury must always be suspected and excluded with this type of trauma. Penetrating injuries usually result from gun shot or knife wounds. Gun shot wounds may result in massive injury and tissue loss not only in the path of the bullet but also in adjacent structures. The degree of peripheral injury is directly related to the velocity of the bullet and therefore hunting or military weapons are especially damaging. Knife wounds tend to cause damage primarily in the path of the blade however, it is important not to underestimate the depth of the injury. With any penetrating injury to the anterior neck, associated injuries to the surrounding vascular structures must be considered and evaluated.(2)
On physical exam, findings of stridor, subcutaneous emphysema, hemoptysis and laryngeal tenderness are common findings. Additionally, loss of thyroid cartilage prominence and ecchymosis in the overlying skin may be noted.(2,3) In cases where the airway is stable, flexible fiberoptic laryngoscopy can provide important information. True vocal cord mobility, soft tissue injuries including edema, lacerations and hematomas as well as the patency of the airway can be evaluated. Again, associated injuries including cervical spine and vascular injuries must be excluded in this initial evaluation.
When the initial work up and endoscopy indicate an intact endolarynx with a displaced thyroid cartilage fracture, open reduction and internal fixation is indicated. Many forms of fixation have been described including nonabsorbable suture, wire, and miniplates. Austin et al have described a wire-tube technique that involves passing a stainless steel wire around the fracture and submucosally on the medial surface of the cartilage.(7) On the lateral aspect of the cartilage, the wire is passed through a blunted 18-gauge needle. This helps prevent wire pull-through and maintains fixation of the cartilage in a more normal position with less angulation or blunting. For vertical fractures, a wire-tube device is placed both above and below the true vocal cord.
In cases with large mucosal lacerations, small lacerations involving the anterior commissure or free margin of the true vocal cords, exposed cartilage, multiple fractures, or true vocal cord immobility, open laryngeal exploration is indicated in addition to ORIF of the fractures. This should be carried out within 24 hours of the injury and is accomplished through a midline thyrotomy or via a vertical fracture if it is located within 2-3 mm of the midline. A horizontal skin incision is made at the level of the cricothyroid membrane and subplatysmal flaps are elevated. The strap muscles are separated and the larynx exposed. An oscillating saw is used to make the midline thyrotomy if no nearby fracture is available. The cricothyroid membrane is then incised and a vertical incision is carried superiorly through the anterior commissure to the thyrohyoid membrane. The thyroid laminae can then be retracted laterally exposing the endolarynx. Afrin soaked pledgetts are placed to achieve hemostasis and the endolarynx is carefully evaluated.
The goals at this point is to return all remaining tissue to its appropriate location and to cover all cartilage. Primary closure is usually possible because most injuries do not involve significant tissue loss and debridment should be kept to a minimum. All lacerations are carefully and meticulously closed using 5.0 or 6.0 absorbable suture. Occasionally, minimal undermining of adjacent mucosa is required to achieve closure. If primary closure is still not possible, mucosal flaps can be rotated from the epiglottis or pyriform sinuses.(3,8) Skin or mucosal grafts are rarely needed. If dislocated, the arytenoid cartilages should be reduced and the overlying mucosa repaired. The normal scaphoid shape of the anterior commissure is then reconstituted by using 4.0 absorbable suture to approximate the anterior true vocal cords to the outer perichondrium.(1) The thyrotomy is then close with nonabsorbable suture, wire or wire-tube techniques. ORIF of associated fractures is then carried out as described above.
Patients with anterior commissure injury, comminuted laryngeal fractures, or massive mucosal injuries require stenting in addition to the techniques mentioned above. With anterior commissure injury, the stent is used to prevent webbing and to maintain its scaphoid shape. In comminuted fractures and massive mucosal injuries, the stent is used to provide support during the healing process and to prevent adhesions. The use of a stent should be viewed as a compromise between the above benefits and the inherent further injury caused by the stent. For this reason, stents should be removed as soon as possible, usually after about two weeks. There are many types of stents available including home-made finger cots, modified endotracheal tubes (Portex), and commercial silastic stents. The ideal stent should extend from the false vocal folds to the first tracheal ring, should be relatively soft and should be able to be secured inside the larynx in a manner that allows movement with the larynx during swallowing. Additionally, its shape should resemble the shape of the larynx as closely as possible being scaphoid shaped at the level of the true cords and round in the subglottis.(9)
Repair of recurrent laryngeal nerve injuries is controversial. Although direct repair provides little chance of functional return, it may help maintain true vocal cord bulk and should be considered when transection of the nerve is identified.(2)
As mentioned above, most injuries do not involve significant tissue loss. In those cases where portions of the larynx are lost or completely destroyed, techniques similar to those used in various partial laryngectomy procedures can sometimes be utilized to restore function. In general, if the basic laryngeal skeletal and soft tissue elements remain, an attempt should be made at restoration.(9) In some cases however, the best final result may require total laryngectomy.
Pediatric laryngeal injuries also deserve special consideration because of several important differences when compared to adult injuries. First the proportionally smaller pediatric larynx tolerates much less edema before airway obstruction occurs. Second, the pediatric larynx is more flexible with more loose connective tissue. This results in a lower incidence of cartilage fracture but more soft tissue injury including edema, arytenoid dislocation, recurrent laryngeal nerve injury, and telescoping injuries where the cricoid becomes displaced under the thyroid cartilage. The third and only protective difference is the relatively high position of the pediatric larynx under the mandible. Except for the differences in airway management mentioned above, the medical and surgical treatment is similar to adult injuries. Finally, except in cases with a clear mechanism of injury ( i.e. MVA), the possibility of child abuse should be considered.(5)
Laryngeal and tracheal stenosis may also complicate the final result. This is often related to maturation of areas of granulation tissue. The management is site specific and may include laser excision, resection with mucosal coverage, stent placement, laryngotracheoplasty, or segmental tracheal resection.
True vocal cord immobility may be related to either recurrent laryngeal nerve injury or arytenoid fixation. Treatment is determined by whether one or both cords are involved and by whether the resulting functional problem involves airway patency or voice.
2. Bailey, B.J. Head and Neck Surgery-Otolaryngology. Laryngeal Trauma, J.B. Lippincott; Philadelphia. Ch 74 vol. 1. 1993
3. Bent, J.P., and Porubsky, E.S. The management of blunt fractures of the thyroid cartilage. Otolaryn Head Neck Surgery. 1994:110(2);195-202
4. Schaefer, S.D. Use of CT scanning in the management of the acutely injured larynx. Oto Clinics of North America. 1991:24 (1); 31-36
5. Myer, C.M., Orobello, P., Cotton,R.T., Bratcher, G.O. Blunt laryngeal trauma in children. Laryngoscope. 1987:97;1043-48
6. Austin, J.R., Stanley, R.B., and Cooper, D.S. Stable internal fixation of fractures of the partially mineralized thyroid cartilage. Ann Otol Rhinol Laryngol 1992:101;76-80
7. Olson, N.R. Laryngeal Trauma. Publication Am. Academy of Otol-Head and Neck Surgery. Washington, DC. 1982
8. Schaefer, S.D. The treatment of acute external laryngeal injuries "State of the Art". Arch Otolaryngol Head Neck Surg. 1991:117;35-39